The invention relates to a drilling derrick device for handling drill-pipe stands.
Drilling derrick devices of a conventional type of construction for handling drill-pipe stands are provided with two racking platforms for receiving the drill-pipe stands, the racking platforms being rigidly connected to derrick girders at corner regions situated at opposite sides of the drilling derrick and racking surfaces (so-called "setbacks") for the stands are provided beneath the platforms and integrated into the working deck. The particular drill-pipe stands of the drill string are usually introduced into the finger spaces of appropriate rows of fingers of the racking platforms by the crew of the drilling derrick, using block and tackle and lifting cranes, with laborious and time-consuming work and not inconsiderable risk of accident. It is also known to equip a drilling derrick with a drill-pipe robot (pipe handler) which can travel between the drill string and the racking platforms and setbacks and which, for example in order to change the drilling tool, conveys one detached drill-pipe stand at a time to a particular finger space of a row of fingers of a racking platform ready to receive it and introduces and racks the drill-pipe stand by means of its gripping arms and then returns to its initial position to convey a following drill-pipe stand. Because of the long conveying distances along the racking platforms which have to be travelled over by the drill-pipe robot for the dismantling and assembly respectively of a drill string of up to at least five meters in modern drilling derricks, and particularly in the case of relatively great drilling depths, here, too, the operation of assembling or dismantling the drill string is extremely time-consuming and, as a result, also cost intensive. In addition, as a result of the travelling movement of the drill-pipe robot under the load of the drill-pipe stands, vibrations may occur which impair the stability of the derrick.